1. Field of the Invention
This invention relates to impact crushers which have a rotor carrying hammers arranged to strike and throw rock to disintegrate upon impact with target members spaced from the rotor, and in particular to an improved feed assembly for such a crusher.
2. Description of the Prior Art
It is known that impact crushers of the aforesaid type have been provided with a downwardly inclined feed chute having an angle of incline which is fixed relative to the crusher wall through which the feed chute projects. An example of such a crusher is disclosed in British Pat. No. 498,415 of Jan. 9, 1939. With such a crusher, if a rock bridges the space between the feed chute and a target breaker bar and fails to drop into the range of the hammers, it becomes necessary to open the housing in order to clear the crusher of such material.
U.S. Pat. No. 2,767,928 of Oct. 23, 1956 discloses an impact crusher with a feed chute having an angle of incline which can be adjusted in a manner permitted by support brackets having upwardly turned arcuate chute support surfaces. With such an arrangement the angle of the chute can be adjusted to move the lower end away from target bars while the upper end moves toward the target bars, or to move the lower end toward the target bars while the upper end moves away from the target bars. However, this arrangement is not operative to move the entire chute away from the target bars while tilting the upper end downwardly toward a horizontal position, as is possible with the hereinafter described present invention.
German Pat. No. 1,032,647 of June 19, 1958 discloses an impact crusher having a feed chute held at its opposite longitudinal edges between guide rails at a constant angle of incline, but with the chute being withdrawable and movable away from a rotor and target bars by engaging a hook depending from the underside of the chute to pull the chute up the incline of the guide rails. Thus the upper end of the chute is raised to a higher elevation as the chute is pulled away from the rotor and target bars, and is difficult to operate and/or ineffective to drop a rock bridging to the top of the chute until the chute is completely withdrawn from between the guide rails.
U.S. Pat. No. 2,862,669 of Dec. 2, 1958 discloses an impact crusher with a chute that can be raised or lowered but without changing the angle of the chute or the distance of the chute from an adjacent rotor.
U.S. Pat. No. 2,889,119 of June 2, 1959; U.S. Pat. No. 3,157,367; and U.S. Pat. No. 3,701,485 disclose chutes that pivot about an axis beneath the chute and near the upper end of the chute. Such a chute adjusting arrangement, like the aforementioned U.S. Pat. No. 2,767,928, provides adjustability whereby when the lower end of the chute is moved away from the target bars the upper end of the chute moves toward the target bars.
U.S. Pat. No. 2,644,644 of July 7, 1953 and U.S. Pat. No. 3,202,367 of Aug. 24, 1965 disclose an arrangement for lowering the upper end of a chute about an axis beneath the chute and near the lower end of the chute. However, when a rock bridges the space above the whirling hammers and between a target bar and the lower end of the chute, the arrangement of this patent is ineffective to drop the rock into the range of the hammers because as the upper end is lowered, the lower end is raised thus lifting such a bridged rock further away from the range of the whirling hammers.
None of the aforementioned arrangements for adjusting the angle of a feed chute to drop a rock bridging the space above the hammers and between the chute and target bars, are therefore effective to lower or drop both rock bridging high and rock bridging low on the inclined feed chute.